The present invention relates to a control apparatus for motor vehicle mechanical clutches in general, and more particularly to a hydraulic control apparatus for operating pull type clutches and to a structure for coupling the clutch release bearing to a clutch operating member.
Hydraulic apparatus for remotely controlling the operation of a motor vehicle mechanical clutch, such as a disk clutch for example, consist of a master cylinder having an input member mechanically connected to the driver operated clutch pedal, the master cylinder output being hydraulically connected by a conduit to the input of a remotely located slave cylinder operating the clutch release mechanism. The slave cylinder often takes the form of an annular cylinder installed peripherally around the driveshaft driving the input of the transmission or gearbox from the clutch mechanism. Such apparatus are well known, as for example disclosed in U.S. Pat. Nos. 4,585,106, 4,585,107, 4,585,108, 4,585,109 and 4,609,087 and in U.S. patent application Ser. No. 537,869, filed Sept. 30, 1983, all assigned to the same assignee as the present application.
The slave cylinders of such hydraulic apparatus are provided with an annular piston having an end disposed in the annular cylinder and another end supporting, or connected to the clutch throw-out bearing. Slave cylinders for operating clutches of the push type are generally of the push type. Hydraulic fluid supplied from the master cylinder, is introduced in the slave cylinder in a chamber between the piston head and an end of the slave cylinder to displace the piston, and therefore the clutch throw-out bearing, in a direction toward the clutch mechanism, causing the revolving race of the throw-out bearing engaged with the end of the clutch release fingers to push against the finger ends for releasing the clutch. Some clutch mechanisms are designed with a leverage arrangement that requires that a pull away from the clutch mechanism be exerted on the end of the finger for displacing the clutch pressure plate away from the clutch disk plate. A pull type slave cylinder is required for operating such clutch mechanism, having a structure which, when hydraulic fluid is supplied to the slave cylinder from the master cylinder, causes displacement of the piston in the direction causing the revolving race of the throw-out bearing to pull, rather than push, on the end of the clutch release fingers. One problem involved with such a structure is that the throw-out bearing thus forms part of the clutch assembly, as it must be installed behind the clutch release fingers, with the inconvenience that the throw-out bearing must be attached, in some manner, to the end of the annular piston projecting from the end of the annular cylinder, during assembly of the motor vehicle on the assembly line.